Fuel pumps for compression ignition engines



April 1962 J. B. KRUK-STRZELECKI 3,027,844

FUEL PUMPS FOR COMPRESSION IGNITION ENGINES Filed June 2, 1960 Fig. lmoan/270p ffifi'z ulfcitrzelccliig Unit 3,27,844 Patented Apr. 3, I962ice 3,027,844 FUEL' PUMPS FOR COMPRESSION IGNITION ENGINES JerzyBoleslawKruk-Strzelecki, London, -England,'asslgnor to C.A.V. Limited,London, England Filed June 2, 1960, Ser. No. 33,544 Claims priority,application Great Britain June 15, 1959 2 Claims. (Cl. 103-41) Thisinvention relates to fuel pumps for compression ignition engines, moreparticularly single cylinder engines, the pump being of the kindcomprising in combination a cylinder having a fuel inlet port in itswall, a reciprocable and spring-loaded plunger in the cylinder, saidplunger having in its periphery a helical groove, and means for varyingthe angular setting of the plunger about its axis to determine theinstant in a stroke of the plunger at which communication is establishedbetween the groove and inlet to vary the quantity of fuel delivered bythe pump.

The object of the invention is to provide a pump of the aforesaid kindin a simple and convenient form.

A pump according to the invention and of the kind specified has incombination a sleeve slidably surrounding the outer end of the cylinder,a shoulder on the exterior of said sleeve, an annular abutment plateagainst said shoulder, a spring surrounding the cylinder and bearing atone end against said plate, a key member engaging a longitudinallyextending groove in the cylinder and a hole in the sleeve to preventrelative angular movement, said key member being retained in position bysaid plate, and a radially extending member at the outer end of theplunger whereby angular movements can be imparted to the plunger, thearrangement being such that movement of the sleeve by the spring will beimparted to the plunger through said radially extending member.

In the accompanying drawings FIGURE 1-is a sectional side viewillustrating one example of the invention, whilst FIGURES 2 and 3respectively are sections on the lines 22 and 33 in FIGURE 1.

Referring to the drawings there is provided a hollow body part 4 havinga central bore and a fuel inlet 5 at one side. Secured within one end ofthe bore of the body part is a head 6 formed at the inner end of acylinder 7 containing a reciprocable plunger 8. The head 6 is locatedagainst a shoulder within the bore of the body part 4 and the cylinder 7is restrained from angular movement relative to the body part by meansof apin 9 extending through the body part into a groove in the peripheryof the cylinder. The cylinder 7 has a radial inlet port 10 which is inregister with the inlet 5, and the plunger 8 which is adapted to bemoved inwardly by the action of a cam 11, incorporates in its peripherya helical groove 12 which is adapted to co-operate with the port 10 in amanner to be described. Also within the bore of the body part 4 is aspring-loaded non-return valve 13 through which fuel can be delivered toan outlet 14 at the end remote from the cylinder 7.

The outer end of the cylinder 7 is slidably surrounded by a sleeve 15having an external peripheral shoulder, and against the shoulder is anannular abutment plate 16 which serves to support one end of a coiledcompression spring 17 surrounding the exposed portion of the cylinder 7and hearing at its opposite end upon the body part 4. The sleeve 15 isprevented from rotation relative to the cylinder 7 by means of a keymember in the form of a ball 18 located partially within alongitudinally extending groove 19 in the periphery of the cylinder 7,and partially within a hole formed in the sleeve 15 adjacent theshoulder. As shown in FIGURE 1, both ends of the longitudinal groove 19are closed. Moreover, the arrangement is such that the plate 16 overlapsthe ball 18 and retains it from disengagement from the hole in thesleeve 15.

Secured to the outer end of the plunger 8 for move ment therewith is aradially extending arm 2% adapted at its outer end for'engagement with anotch in a regulator rod 21 movable axially in a direction at rightangles to the axis of the cylinder by a governor or other means (notshown). The arm 20 extends through an arcuate recess at the outer end ofthe sleeve 15, which is adapted to be moved inwardly simultaneously withthe plunger 8 by the action of the cam 11. A small clearance normallyexists between the arm 20 and the base of the recess in the sleeve 15.However, when the sleeve 15 is moved outwardly by the action of thespring 17 it bears against the arm 20 and thereby imparts outwardmovement to the plunger 8. By virtue of the arcuate recess, angularmovement of the arm 20 can be effected without angular movement of thesleeve 15. Such angular movement will be imparted to the plunger 8, andthereby eifect the setting of the helical groove 12 in the plungerrelative to the inlet port iti so as to determine the instant in aninward stroke of the plunger 8 at which communication is establishedbetween the groove 12 and the port 10. The groove 12 is in communicationwith the inner end of the cylinder 7 in known manner and thus as soon asthe groove 12 is in communication with the port it) injection of fuelceases. Thus the angular setting of the plunger 8 will determine thequantity of fuel delivered by the pump at each reciprocation of theplunger.

By the present invention the sleeve in addition to serving to transmitthe spring pressure to the plunger acts as a support for the outer endof the latter due to its guided sliding movement upon the exterior ofthe cylinder.

Having thus described by invention what I claim as new and desire tosecure by Letters Patent is:

1. A fuel pump of the kind specified, comprising in combination acylinder provided near one end thereof with a fuel inlet, a plungerslidably fitting within the cylinder and extending from the other endthereof, a spring-loaded non-return valve which is mounted at the firstmentioned end of the cylinder, and through which fuel admitted to thecylinder is dischargeable therefrom by the plunger, the latter having inits periphery a helical groove, and being angularly adjustable about itsaxis for determining the instant at which communication is establishedbetween the helical groove and the fuel inlet during a discharge strokeof the plunger, a hollow body part within which the first mentioned endof the cylinder is secured, and in which the spring-loaded non-returnvalve is mounted, a sleeve which surrounds the end portion of theplunger extending from the cylinder, and which is slidably mounted onthe adjacent end portion of the cylinder, the said end portion of thecylinder having formed in its outer periphery a longitudinal groovewhich is closed at both ends, a key member in engagement with, andextending outwardly from, the longitudinal groove in the outer peripheryof the cylinder, an annular abutment plate surrounding the sleeve andthe adjacent portion of the cylinder, the sleeve being provided at aposition intermediate its ends with an external annular shoulder whichforms a seating for the annular abutment plate, and being also providedat a position adjacent the shoulder with a hole through which a part ofthe key member projects into contact with an inner portion of theannular abutment plate so that the key member serves to prevent relativeangular movement of the cylinder and sleeve, and is retained in positionby the annular abutment plate, a coiled compression spring surroundingthe cylinder and bearing at opposite ends respectively on the hollowbody part and the annular abutment plate to retain the latter in contactwith the annular shoulder on the sleeve, and a member which is securedto the plunger at the end thereof outside the cylinder, and whichextends radially from the plunger through an arcuate opening in theadjacent part of the sleeve so that the plunger can be moved angularlyabout its axis by the said member, and axial movement imparted to thesleeve by the coiled compression spring is transmitted to the plunger bythe said member.

2. A fuel pump according to claim 1, wherein the key member has the formof a ball Which at one side engages the longitudinal groove in the outerperiphery of the cylinder, and at the opposite side is in contact withan inner portion of the annular abutment plate.

References Cited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS Great Britain July 23, 1952

